Long before I knew what an orgasm was, and long before puberty, I had what were in retrospect dry orgasms while climbing.
First was about age 9 or 10, climbing a pole on the play ground. Shinny up the pole, then slide down. About the third or fourth time up each time I would flex my hips and body while holding on with my hands I would get a strange pleasurable sensation in my pelvis and loins. Get to the top, flex and hold and waves of pleasure. Not certain whether it was because I was hurting myself, as the reason for the sensation was unclear, but certainly kept me coming back to repeat the same.
Never knew it was experienced by others until reading an article a year back about women having exercise induced orgasms in weight rooms.